umount-root-5

[almesber en lrc.di.epfl.ch]

A new and improved version for the 2.3.40 kernel, and with a patch
for util-linux-2.10e:

ftp://icaftp.epfl.ch/pub/people/almesber/misc/umount-root-5.tar.gz

The main improvement here is that it can forcibly chroot processes
sitting on the root of a file system. This avoids all the problems
with kernel threads that don't CLONE_FS from init, daemonize(), or
exit_fs(). (Adding exit_fs is dangerous - e.g. my change to lockd
in umount-root-4 would probably have crashed lockd when forking a
reclaimer.)

In order to keep umount semantics sane, I've added two new flags.
A patch for the latest version of util-linux teaches umount the
new tricks. I've also added an option -x to keep umount(8) from
trying to be clever. (E.g. translating /dev/hda1 -> / or
attempting turn an umount into a remount. Both are very bad ideas
in this particular scenario.)

This is probably the last version before I send it to Linus. So
please give it a good beating.

- Werner

P.S. No, there's unfortunately no easy way to generalize this into
     an umount -f that can get rid of arbitrary processes.
     fuser -km  is your friend ...

-- 
  _________________________________________________________________________
 / Werner Almesberger, ICA, EPFL, CH       werner.almesberger en ica.epfl.ch /
/_IN_N_032__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/

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